This invention relates to apparatus and methods for milking dairy animals and collecting milk, and more particularly to a dairy harvesting facility with apparatus and methods for protecting milk collecting lines and systems from various types of cleaning fluids and contaminated milk.
In dairy milking systems, sanitary conditions must be maintained to the extent possible. Dirt can enter a dairy milk system through the teat cup and liner (“inflation”) that are attached to an animal to extract milk. Vacuum is used to milk the animal and draw milk into the hoses, lines and storage tank system in the dairy. Any dirt on the animal's teats can be drawn into the system by this vacuum.
To minimize dirt in the dairy milking system, a dairy animal is prepared for milking by an operator who typically washes or otherwise cleans the animal's teats. Cleaning before milking minimizes the chance that dirt and debris will enter the milk system in the dairy while the animal is milked, and also permits the operator to extract (“strip”) foremilk from the teats and massage the teats so they are better prepared for milking.
In dairies time is of the essence, so preparing the animals must be done quickly and thoroughly. At least one and sometimes two or three operators will be stationed at a milking parlor entrance to prepare and then attach a milker unit to each animal.
Milker unit inflations have teat cups and teat cup liners that cooperate with vacuum in the milking system to milk the cows. A teat cup and liner receives nearly all of the teat so any dirt on the teat could make it into the teat cup and liner and then the milk system. Logically, dirt should be removed before a teat is inserted into an inflation.
Between preparation of the animal for milking and attachment of the milker unit, it is possible that more dirt and debris could attach to the animal's teats because of the nature of a dairy environment. So even with good and efficient operators, some dirt can still make it into the milking system.
To reduce labor and improve cleaning and efficiency, there are automated teat cleaning systems that include teat cups similar in appearance to teat cups on a milker unit. Teat cups on a cleaning system wet the teats with water and/or sanitizer, and they may include brushes to aid in cleaning. Some even include pulsators that spray pulses of liquid toward the teat. After cleaning, the cleaning system cups are removed and then a milker unit is attached to the animal for milking. Attaching two separate units to the animals with the teats exposed for a brief interval in between, wastes valuable time and risks the teats becoming dirty again.
Another automated preparation system is combined with a milker unit so that only one machine is attached to an animal for preparation and milking. This saves time and ensures that the teats are not exposed to dirt between preparation and milking. This system is efficient and effective, but attaching a preparation system to a milking system may be a possible source of contamination because vacuum in the milking system could draw sanitizer, water or dirt from the cleaning system into the milking system.
Sanitizer and water used to clean teats must not be allowed to mix with milk that will be consumed by humans or calves. Moreover, dairy pipeline washing fluids and contaminated milk must not be allowed to enter milk lines that transport milk to centralized chillers and storage tanks unless the milk lines themselves are to be cleaned.
In apparatus that both cleans and milks, a four-way valve separates the wash lines and the milk lines in an effort to prevent milk and milk line contamination. To further avoid contamination, a small amount of milk from the start of the milking process is diverted to a waste line to ensure that residual washing fluids are carried away before usable milk is directed to the dairy's milk lines.
Nonetheless, a four-way valve can be insufficient to prevent cleaning fluids and contaminated milk from entering the dairy milk collecting system because vacuum in the milk lines (used to draw milk to a central storage location) results in the milk line having a different pressure than the wash lines, and the wash lines are subjected to various pressures before and after a wash cycle. Differential pressure and vacuum applied on opposite sides of a four-way valve are likely to cause seepage and leaking of milk and/or cleaning fluids past seals in the four-way valve. Thus, the competing pressures in the various lines attached to the four-way valve could eventually cause valve failure and milk line contamination to some degree.
This problem is well known in dairies that use clean-in-place (“CIP”) wash systems. CIP wash systems are connected to dairy milk collecting lines, which are at a position downstream from milker units and their respective long milk tubes. Milk flows from the milk collecting lines to a dairy's central milk storage system.
To avoid contamination through valves as described above, the milk lines and CIP lines are required by FDA Regulations to be separated by a pair of spaced apart valves with a bleed vent in between the two valves. The bleed vent is open to atmospheric pressure so that pressure or vacuum in one line bleeds off without affecting the other line. This arrangement of valves and a vent is known as a “block-bleed-block” system.
When two valves are separated by a vent or “bleed” to atmosphere, there is no possibility that milk or washing fluids can be drawn past either valve because vacuum in the milk line is dissipated by the bleed vent and the two valves are physically separated, so there is no fluid communication between the two. In operation, a block-bleed-block system has one of the valves open to expose a desired pipe line to the milker unit, while the other valve is closed. Even if one valve fails, the spaced apart and vented relationship between the valves prevents cross contamination. Other teat dip applicators have been disclosed that include block-bleed-block features.
The block-bleed-block arrangement is not new to the dairy industry, but implementing a block-bleed-block system is not always possible, convenient or practical. In CIP systems, the valves and bleed vent are disposed in an easily accessible area and can be of any convenient size because they are positioned well away from the milker units and other working components of the milking system. Expense for building and maintaining these systems can be prohibitive, so when space does not permit a block-bleed-block arrangement, some milking systems are designed to segregate wash and milk lines in other ways.
One such alternative way to isolate milk and cleaning lines from one another is to manually disconnect a wash line and/or a milk line when not in use. Such a procedure is effective, but obviously requires an operator to be present between milking and washing operations. In robotic systems, the intent is to reduce operator involvement in all phases of the washing and milking operations. Requiring an operator to be involved is further complicated in robotic systems because milking machines are washed only when necessary, and not on a regular basis that would be conducive to operator scheduling. Involving an operator would likely slow down the milking process for the dairy as a whole, and would at least partially defeat the point of a robotic milking system.
Therefore, it is desirable to have an automated or robotic milking system that does not risk contamination of milk and milk lines or require operator involvement, and is practical to build, install, and maintain.